The Trump Administration on June 19 finalized a rule to reduce greenhouse gas emissions from coal plants – but the rule will only minimally reduce emissions and is unlikely to change power generation.   

However, the longer-term implications of the rule, which could hamstring future administrations from regulating carbon dioxide, concern some states and environmental groups which have promised to take the rule to court after it is published in the Federal Register.

The Affordable Clean Energy rule (ACE) replaces the Obama Administration’s Clean Power Plan, which was formally repealed on June 19 as part of the finalization of ACE. The Supreme Court stayed the Clean Power Plan after it was challenged by 28 states, and it was never implemented.

Under the ACE rule, the EPA will require states to reduce carbon emissions by requiring efficiency improvements in their coal plants. EPA won’t set a floor or a ceiling for state-specific emissions reduction targets, but it has listed six best available technologies states can use to require improved efficiency: neural network/intelligent saw blowers; boiler feed pumps; air-heater and duct-leakage control; variable-frequency drives; steam-turbine blade path upgrade; and redesigned or replaced economizer.

The agency did not determine that carbon capture and sequestration was a viable option because “under the law, best technology has to be both technologically feasible and cost effective,” an EPA spokesman said in a background briefing. Fuel switching, or converting a coal plant to burn natural gas, is also not an approved method.

Using the EPA framework under section 111 (d) of the Clean Air Act, states will have three years to develop a plan to submit emissions guidelines for plants in their states. If a state does not submit an acceptable plan, EPA can write its own plan. Under the ACE timeframe, it could be as long as 6 ½ years before any state rules are put in place.

The agency chose not to offer changes for new source review as it had proposed in the draft ACE rule. Those new regulations will come within a few months, an agency spokesman said.

EPA Administrator Andrew Wheeler touted that under the program, CO2 emissions will be reduced as much as 35 % below 2005 levels by 2030. But EPA has estimated that ACE alone will reduce GHGs 0.7% to 1.5% more than the business as usual case.

In many states, cheap natural gas and renewable power has forced the retirement of so many coal plants Energy Information Administration data shows that CO2 emissions are 27% below 2005 levels and it forecasts the power sector to be 33% below 2005 levels in 2030.